Annealing furnace



Sept. 5, 1939.

J. C. WOODSON ANNEALING FURNACE 1938 3 Sheets-Sheet 1 Filed Oct. 28,

I l I I I ,1 1/ 1 INVENTOR (James C. Woodson Sept. 5, 1939. J. c.WQODSON 2,171,777

ANNEALING FURNACE Filed 0d. 28, 19:58 3,Sheets-Sheet s LEINVENTOR IJamesCZWoooson Patented Sept. 5, 1939 UNITED STATES 2.171.777 ANNEALINGFURNACE James C. Woodson, Cleveland, Ohio, assignor to Lee Wilson SalesCorporation, Cleveland, Ohio,

a corporation of Ohio Application October 28,

4 Claims.

This invention relates to a furnace and, in particular, to a furnaceadapted for the metallurgical processing of material such as ferroussheets or strip. Specifically, the invention. concerns a furnace adaptedto receive a pair of spaced stacks of sheets or rows of coils andprovided with means for supplying heat to opposite sides of such stacksor coils. This is in part a continuation of my copending applicationSer. No. 166,052.

Furnaces of the cover type have gone into wide use in recent years andin everyday operation, have served their intended purpose verysatisfactorily. Special problems have arisen in certain cases, however,and it is anobject of this invention to provide a solution for one suchproblem, viz., the annealing of sheets having a length several times(four to six' times) their .width.

I have invented a novel furnace particularly adapted .for annealing longnarrow sheets, which I has a lower cost per ton of monthly capacity thanfurnaces siuch as those used heretofore and operates at an efliciencyequal to or greater than that of the latter. In-a preferred form of theinvention I provide a furnace, preferably though not necessarily of thecover type, with charge supports adapted ,to receive spaced stacks oflong narrow sheets and having heating means on the side walls of thefurnace and at the central plane therethrough whereby each stack isheated from both sides thereof. The details of the invention will beexplained in the course of the following description of thepreferred,embodiment above mentioned which is illustrated in theaccompanying drawings. In the drawings:

Fig. 1 is a transverse section through a furnace in accordance with theinvention;

Fig, 2 is a longitudinal section taken substantially along the plane ofline II--II of Fig. 1; line I -I of Fig. 2 indicates the plane on whichthe section shown in-Fig. 1 is taken;

Fig. 3 is a partial sectional view taken the plane of line IIIIII ofFig. 2;

Fig. 4 is a sectional view taken along the plane of line IV-IV of Fig.3;

Fig. 5 is a diagram illustrating the fuel supply system for the heatingmeans of the furnace; and

Fig. 6 is a diagram illustrating the arrangement of certain parts of thefurnace.

along 50 for the present, to Figs. 1 and 2, the preferred embodiment ofmy furnace comprises a base It having a heating cover I I liftablydisposed thereon. The base It] includesa refractory layer or hearth 12built up on a supporting frame come 55 prising structural members l3 anda base plate the ends of the latter.

Referring now in detail. to the drawings and.

1938, Serial No. 231,422

M. The hearth l2 includes spaced piers I5 and a curb l6 extendingtherearound. Charge supports ll are disposed on each of the piers IS,the arrangement of the supports on each pier-beingshown diagrammaticallyin Fig. 6. Bottomplates l8 rest on the supports l1 and are adapted toreceive and support a charge such as a stack of sheets IS.

The hearth I2 is provided with a layer of sealing material 20 such assand disposed within the curb IS.- A protective cover 2| is disposedover each of the stacks I9 with its lower edges penetrating the layer ofsealing material. A sealing channel 22 extends around the base H] forcooperation with a sealing flange 23 depending from the heating cover H.

The heating cover H comprises an open-bottomed enclosure including sidewalls 24, end walls 25, and a roof 26 assembled within a frame includingbuckstays 21, beams 28, and sheathing plates 29. The inner surfaces ofthe walls and roof of the cover, like the hearth I2 on the base ID, arecomposed of refractory material.

Heating tubes 30 are mounted on the side walls 24, being disposed inspaced relation therealong. Suitable openings 3 I are formed in the sidewalls to receive the ends of the tubes. The upper ends of the tubes passthrough a sealing box 32 filled with granular material such as sand, onemerging from the furnace walls. Each tube has a burner 33projecting'into' the lower end thereof and adapted to be supplied withfuel from one of a pair of manifolds 34 and 35. Alternate burners areconnected to the same manifold, adjacent burners being connected todifferent manifolds as shown diagrammaticallyin Fig. 5. Spark gapigniters 36 are mounted on the upper ends of the tubes 30 and areconnected to transformers 31. Exhaust ducts 3 8 extend along each of theside walls and have openings 39 into which the upper ends of the tubes3|) extend. Stacks 40 extend upwardly from the ducts at pointsintermediate A bank of heating tubes indicated generally at 4| extendsinwardly through each of the end walls 25 substantially alongthecentral, longitudinal, vertical plane through the furnace. Each of thebanks 4| includes heating tubes 42 graduated in size, the largest tubesbeing disposed adjacent the bottom and the smallest tubes I adjacent thetop of the bank. The outer ends of the tubes pass through a sealing box43 filled with granular material such as sand and are providedwith'burners 44. The inner ends of the tubes enter sleeves 45 extendingfrom vertical exhaust ducts or headers 46 at right angles thereto. Asbest shown in Figs. 3 and 4, each of the tubes 42 has spacer fins 4'!secured thereto as by welding, which position the ends of the tubes relative to the sleeves 45. The fins are not secured to the sleeves however,and thus fioatingly support the inner ends of the tubes for freemovement in the sleeves 45 on expansion and contraction of the tubes.Fuel is supplied to the burners 44 as indicated in Fig. by manifolds 48.

A hanger 49 depending from the roof 26 is provided for supporting eachbank of tubes. The exhaust ducts 46 have transverse pins 59 extendingtherethrough adapted to engage notches formed in beams 5|. The beams arecarried-on hangers 52 depending from the roof. Auxiliary beams 53similarly support the lower ends of the ducts 46 and are carried on thebeams 5| by hangers 54. The ducts 46, after they emerge from the roof26, extend laterally from the longitudinal, central plane through thefurnace and are connected to an offtake 55.

Referring now to Fig. 5 showing the fuel supply, systemdiagrammatically, fuel is supplied from any suitable source through ashut-off valve 56 and a master regulating valve 51 to the manifolds 34and 35. The manifolds 34 have valves 58 therein for discontinuing thesupply of fuel under certain conditions which will be explaincd shortly.Similar valves 59 are disposed between the manifolds 48 and certain ofthe tubes 42. These valves 58 and 59 are of the type which closesautomatically when the pressure of the fuel supplied thereto falls belowa predetermined value. Such valves are well-known and require nodetailed description.

The system shown in Fig. 5 makes possible highly efiicient operation ofthe furnace in that during the initial stages of the heating cycle, allthe tubes 30 and 42 may be fired at full capacity. When the charge isapproaching the maximum temperature, however, and it is necessary onlyto allow sufficient time for the heat to soak entirely through the massbeing treated, operation of the master control valve 51, eitherautomatically or manually, throttles the fuel supply so that thepressure on the furnace side thereof is less than that required tomaintain valves 58 and 59 open. As a result, the supply of fuel toalternate tubes 30 and to all of the tubes 42, except the two bottomones in each bank, is discontinued. The tubes 30 connected to themanifolds 35 and the two bottom tubes 42 in each bank continue to supplyheat to the charges thereby increasing their temperature at a reducedrate while permitting the heat previously supplied to the charges tosoak entirely there: through. The two bottom tubes of each bank arecontinuously fired' because the heat supplied thereby to the chargesnaturally tends to rise a through the latter.

It will be evident from the foregoing description that the inventionprovides a furnace for annealing or otherwise processing material-whichoperates at high efficiency and, at the same time,

requires a minimum investment per ton of capacity. By. supplying heat tothe charges from opposite sides, the temperatures of all parts thereofare raised at substantially the same rate. The

automatic shut-off of the supply of fuel to certain of the heating tubesmakes possible a substantial saving in the fuel cost. While the furnaceis intended particularly for the treatment of long narrow sheets, it mayalso be employed for treating coils. By employing tube banks extendinginto the furnace for only half the length thereof, the provision of thenecessary supports therefor is simplified. In addition, better controlof the distribution of heat in each individual tube is obtained. Thefuel supply to each tube may be manually controlled by suitable valves.The connection between the tubes of each bank and the associated duct,furthermore, is such that adjustment of the fuel supply for one tubewill not disturb the draft or combustion in adjacent tubes.

Although I have illustrated and described herein but a preferredembodiment of the invention, it will be understood that changes thereinmay be made without departing from the spirit of the invention or thescope of the appended claims.

I claim:

1. In a furnace including a roof and side walls, a bank of substantiallyhorizontal heating tubes extending through a side wall thereinto, and anexhaust duct extending from the furnace substantially vertically throughsaid roof, the inner ends of said tubes having a telescopic connectionwith said duct.

2. In a furnace, a bank of heating tubes extending thereinto, a mastervalve controlling the supply of fuel to said tubes for combustion, andvalves which close automatically on reduction of the pressure of saidfuel controlling the supply thereof to certain tubes of said bank.

3. In a furnace, a bank of heating tubes mounted therein, fuel supplymanifolds to which said tubes are connected in groups, a master valvecontrolling the supply of fuel to said manifolds, and a valve whichcloses on reduction of the pressure of said fuel controlling the supplythereof to one of said manifolds.

4. In an annealing furnace, a base, a plurality of supports for chargesof material arranged on said base in spaced rows, a cover having sidewalls, end walls, and a roof, adapted to be disposed on the base andoverlie all said supports andcharges thereon, heat-exchange tubesextending upwardly along said side walls from points near the loweredges thereof effective to deliver heat to the outer sides of charges onsaid supports, substantially horizontal heat-exchange tubes extendinginwardly from said end walls, and suspended from said roof betweenadjacent rows of charge supports for radiating heat to the inner sidesof said charges, and exhaust tubes connected to said last mentionedtubes and extending substantially vertically through said roof.

'JAMES c. WOODSON.

